This invention relates in general to apparatus for filtering dirty liquid such as machine tool coolant which contains metal chips and particles. More specifically, the invention relates to filtering apparatus of the same general type as disclosed in Uchiyama U.S. Pat. No. 4,992,167.
In the apparatus disclosed in the Uchiyama patent, a rotatable drum with a filtering screen is supported within a reservoir and is partially immersed in a pool of dirty liquid. Liquid from that pool flows into the drum through the screen and is filtered by the screen. The filtered liquid flows axially out of the drum through outlet openings in one end wall of the drum and an adjacent end wall of the reservoir. Part of the filtered liquid is pumped to a pipe located within the drum and having spray nozzles for directing the filtered liquid against the screen in order to flush and clean the screen.
One end wall of the filter drum of the Uchiyama patent is fixed to a shaft which is driven in order to rotate the drum. The other end wall of the drum is formed in part by a large ring which is journaled to rotate within a large sleeve supported by a wall of the reservoir, the ring and the sleeve coacting to form the discharge openings for the filtered liquid. This arrangement for rotatably supporting the drum is rather complex and expensive and particularly when a screen-flushing pipe is located within the drum.